This invention relates to water leak detection, and more particularly relates to an apparatus and method for enabling early warning signaling a diversity of water leaks occurring in buildings and the like.
Water leaks are a common problem associated with air conditioners, hot water heaters, washing machines, and various other water-dependent appliances used in buildings such as homes, townhouses, apartments, mobile homes, and offices. Conventional construction patterns frequently situate air conditioners and hot water appliances in the attics of these buildings. As will be appreciated by those skilled in the art, water leaks are inherent in such water-dependent appliances. Even though most small air conditioners do not use water for refrigerant cooling, water damage is still a threat because condensate drains often foul, thereby causing overflow of the condensate catch pan.
As will also be appreciated by those skilled in the art, water leaks are typically detected only after a substantial leak or a substantial accumulation of water has developed. Obviously, it would be advantageous for practitioners in the art to have the benefit of a permanent, early-warning alarm system for detecting these common water leaks before costly repairs become necessary. Unpredictable water leaks from appliances and the like, of course, are always inconvenient and may cause incidental damage to furniture, electrical equipment, and other property. Furthermore, this problem is compounded by the prevalence of aging appliances and the like, and also aging water pipes or deteriorated joints.
Unfortunately, there is no dependable way to prevent building repairs attributable to water leaks from appliances and the like. Heretofore, only home owners and the like who have appropriate liability insurance coverage or who otherwise have sufficient financial resources, have been able to routinely cope with repairs associated with water leaks. Nonetheless, every victim of such recurring water leaks must suffer the inconvenience and disturbance to the daily routine. Furthermore, senior citizens, families living on fixed incomes, and families trying to live within low incomes not only cannot afford to have insurance coverage for predictable accidents involving water leaks and the like, but also tend to use appliances which are old and, therefore, likely to be subject to water leaks leading to major house repairs.
There have been many developments in the art seeking to detect water leaks occurring in water-related appliances and the like. For example, Barron, in U.S. Pat. No. 5,428,347, discloses a water sensor system for monitoring a plurality of water-related appliances and equipment. When leaking water is sensed, suitable action such as shutting off power or shutting off the water supply is taken. The Barron apparatus comprises a plurality of electronic circuits which include thermal circuit breakers. It will be evident to those skilled in the art that the circuitry of this apparatus is unnecessarily elaborate and interfaces directly with 120 volt and 240 volt lines. Circuit breakers in 240-volt control lines are tripped by drawing excess current to effect "memory" of leaking devices which might be hazardous if the breaker failed to trip. Leaks are detected by either opening or shorting a full-wave diode bridge. The interface with the power lines is complicated and probably would not satisfy UL safety standards. Moreover, it is a disadvantage of the Barron apparatus that standing water is prerequisite to triggering water leak detection; accordingly, water damage is apt to occur prior to alerting the consumer and the like that a problem exists.
In U.S. Pat. No. 5,229,750, Welch et al. teach a leak sensor consisting of solenoid valves for shutting off the water supply and for draining water tanks through discharge lines to the outside of a building and the like, and for simultaneously shutting off the power. The Welch sensor has a float with a metal cap, two pair of electrical probes or conductors placed on opposite sides of the float. When a water leak is detected, an inlet valve is shut and an outlet valve is opened thereby releasing stored water to the outside. As should be apparent to those skilled in the art, the water leak detection disclosed by Welch requires there being two solenoid valves for each water dependent appliance being monitored. The first solenoid valve shuts off the water being fed to the appliance, while the second solenoid valve drains the water therefrom. Thus, the operation of the Welch water leak sensor hinges upon solenoid valves being open or closed, as appropriate; it is, in actuality, a water shut-off procedure. A solenoid valve, of course, comprises a coil of wire that acts like a magnet when current is passed therethrough. That is, a solenoid is an electrically energized coil that may consist of one or more layers of windings. Using a solenoid to switch from an open to a closed position typically consists of a coil and a metal core that is free to slide along the coil axis under the influence of the magnetic field. Thus, unlike a regular valve that is a activated manually, a solenoid valve requires an electrical current for activation.
It is well known in the art that solenoid valves are not amenable to being used on any commercially available plumbing fixtures or main water supply line. Furthermore, it is not clear where practicable placement of such solenoid valves in water-dependent appliances in single-family residences, apartments and the like, industrial buildings or plants. Nevertheless, in each instances, it should be evident that retrofitting is prerequisite to Welch; it is clearly a limitation of this sensor that extensive retrofitting is required to add solenoid-actuated inlet valves and to provide valve-actuated drain paths from existing tanks and the like through exterior walls.
An example of the retrofit limitations of Welch is its application to a commode. In order to properly place the solenoid valves contemplated by Welch to turn off inlet water when a water leak is detected, the detector must be disposed in a pan. Obviously, the commode must be removed and a suitably-sized pan inserted, not to mention also inserting a toilet seat water-seal either beneath the commode or atop the pan, and perhaps another water-seal would be appropriate below the pan. Furthermore, the Welch disclosure depicts solenoid valves that have been inserted into incoming water pipes and outgoing water pipes. It is well known in the art that such solenoid valves are not normally incorporated into water pipes. Thus, the inherent retrofit aspects of Welch are clear.
Akiba, in U.S. Pat. No. 4,843,305, discloses an apparatus for sensing leaks in water pipes based upon the conductivity of spaced-apart pairs of insulated conductors which are wrapped around the pipe. More particularly, this sensor, it should be understood by those skilled in the art, however, that leaking water may not always establish contact with all exposed areas of the insulated conductors, or that leaking water may not adhere to the conductors, thereby obviously failing to signal a leak. Similar to the Akiba apparatus, in U.S. Pat. No. 4,374,379, Dennison teaches a moisture sensing apparatus for pipes that also uses a pair of spaced-apart electrical conductors partially positioned in an elongated flexible insulator which is circumferentially affixed to such pipe. The partially exposed electrical connectors are oppositely disposed relative to the pipe. An alarm actuating circuit is interconnected with the conductors and configured to initiate an alarm when water bridges the closely spaced conductors. It appears that this apparatus is insensitive to small leaks because water droplets are unable to bridge the sensing electrode gap disposed on the opposite sides of the sensor assembly.
Hinkle discloses, in U.S. Pat. No. 4,090,193, a water leak detection apparatus which used frequency multiplexing to sense the location of leaks. Sensing circuitry comprises a master indicator circuit and a plurality of satellite leak detectors for simultaneously monitoring these detectors based upon their unique frequency warning signal. The indicator circuit isolates and displays the leak location based upon the warning signal. While stating that only two wires are needed to connect all of the satellite detectors to the master, the Hinkle apparatus will require significant wiring and the like to accommodate appliance configurations prevalent in homes and buildings. Furthermore, using a speaker to announce alarm tones is impracticable because most listeners would have insufficient pitch differentiation skills to distinguish one alarm from another. It should also be evident to practitioners in the art that if tone-sensitive circuitry is used to separate alarm tones, then the economy of using a single reporting cable is apt to be lost.
A recent development in the art is a fluid leak detector disclosed by Lawson in U.S. Pat. No. 5,637,789. The Lawson device, intended for downstream leak detection in residential pipelines, detects extraneous fluid flow over a predetermined time interval by means of thermal transport using a thermistor. It appears, however, that this device suffers from being susceptible to malfunctions due to corrosion, hard water, and the like, and from being dependent upon a fine temperature differential, that, in turn, requires a high sensitivity which is inherently adversely affected by the thermistor itself. Furthermore, in order to obtain reasonable leak detection performance over a protracted period of time, the device must be calibrated from season to season. Typical of the prior art, the Lawson detector is not situated proximal to regions susceptible to having water leaks and is unable to pinpoint the actual location of such water leaks.
Accordingly, these limitations and disadvantages of the prior art are overcome with the present invention, and improved means and techniques are provided which are useful for reliably, inexpensively, and safely detecting the onset of water leaks in air conditioners, hot water appliances, pipes, etc., in a diversity of buildings and the like. The present invention prevents or at least minimizes repair damage and the like attributable to undetected or protracted water leaks.